I've seen that happen twice before , once with a S&W 357 mag and the other a Ruger Black Hawk in 44 mag , In both cases it was from a bad handload , do you have any idea how many rounds he had through the gun before this happened ? and what type ?
The reason I ask is that even Trackers don't just fail like that for no reason , something went very wrong and my first look would be the ammo , maybe not those rounds but the ones before and yes even factory ammo can have a double charge , granted it does not happen much but it does happen , I've even gotten factory rounds with no primers before . Photoeyes and human inspectors are not perfect .
The important part is that he was not hurt badly as it could have been much worse .
stimpy